JPS62292362A - Roll processing method for shaft fillet part with different stress distribution - Google Patents

Abstract

PURPOSE:To effectively perform roll processing by regarding both end sides, in the circumferential direction, of a maximum stress part and a region, in the circumferential direction, of a minimum stress part as a transient region of respective pressing forces and processing a work with a lower pressuring force than a constant one. CONSTITUTION:For example, transient regions L1, L2 are made 15 deg. and a necessary process range L1+L2+L3 is made 210 deg. from the stress distribution of the pin fillet part 3 of a crank shaft which is an object of processing. And, when processing beings, a curved surface roller 5 is firstly set at point A, a pressure is gradually increased to point B by means of pressure control with a sequencer, kept constant from point B to point C, and gradually lowered from point C to point D reversely. Secondly, a crank shaft is put in reverse turn, a pressure between point B and point C is gradually increased more than the previous pressure, and the processing pattern is performed in reverse order to the prior one to improve fatigue strength with the help of performing the processing through necessary stages. Accordingly, roll processing can be performed even on a pin on which a fillet is broken at the top part.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a roll of a shaft to be processed having a shaft fillet portion, such as an engine crankshaft, a cam with a pin, etc. The present invention relates to a processing method, and more specifically, to a method for partially rolling an axial fillet portion in which stress distribution differs in the circumferential direction.

(Prior art) As a roll processing method for the shaft fillet part,
There is a technique disclosed in Japanese Patent No.-10818.

That is, a roller and a curved roller are pressed against the fillet portion of the shaft to be processed to form a hardened layer to improve the strength of the shaft.

Here, a general roll processing method will be explained with reference to FIG. 3, taking a large marine crankshaft as an example.

In FIG. 3, a flat roller 4 and a curved roller 5 are pressed against a bin fillet portion 3 in a crank throw 2 state before shrink-fit assembly on a turntable 1 to perform roll processing over the entire circumference.

In this case, in order to prevent the curved roller 5 from coming off the bottle fillet part 3 at the bottle top part, extra thickness 6 is provided at the bottle top part and the entire circumference is uniformly rolled.

On the other hand, in the integrated crankshaft shown in FIG. 4, the bin fillet part 3 is different from the journal fillet part 7, as shown by the symbol 8 at the bin top part (because the fillet is interrupted, the entire circumference cannot be rolled, As shown in FIG. 6, the curved roller 5 did not fall off at the top of the bottle, and the crank arm 9 was rolled with an extra thickness 6 that could at least withstand the processing pressure.

By the way, regardless of whether it is an assembled type or an integrated type, the bottle fillet 7) part 3
In this case, the stress distribution becomes as shown in FIG.

That is, the maximum stress (in this illustrated example, it is expressed as 12.91 kg/Ryu 2, which is taken as 1.00) occurs in the pin bottom part 3B, and the pin bottom part 3B of the pin fillet part, 3
The stress distribution becomes such that the stress value decreases toward both sides in the circumferential direction, that is, toward the bottle top portion 3T (in the drawing, the stress value decreases toward the pin bottom portion 3B).

The ratios of the stress values and the maximum stress values are shown at 15° intervals on both sides of the center line XX passing through the bottle top portion 3T.

(Problems to be Solved by the Invention) In recent years, as engines have become more compact, the top portion of the crankshaft has been designed to remove as much excess material as possible.

Also, this is common in integral crankshafts. Therefore, when the conventional technology rolls the bin fillet portion of the integral crankshaft, there are the following problems.

■ The extra thickness added to prevent the curved roll from falling off interferes with the base plate, that is, the base on which the crankshaft is mounted in a marine diesel engine, so it must be cut by machining after the roll is processed. It requires a lot of effort.

■ On the other hand, if excess metal is left, the base plate will have to be machined to match, which will lead to changes in the design of the engine itself.

■ Yield decreases due to excess thickness.

■ Because the entire circumference is rolled, extra time is spent compared to partial roll processing according to the stress distribution of the bin fillet.

The present invention solves these problems by providing shaft fillet parts (including crankshafts, cams with pins, etc.) having different stress distributions.
The purpose is to provide a roll processing method.

(Means for Solving the Problems) The first technical means taken by the present invention to achieve the above-mentioned object is to press a roller and a curved roller against an axial fillet portion having different stress distributions in the circumferential direction. In the roll processing method for forming a hardened layer, in the circumferential direction of the axial fillet part, a stress distribution is found that has a minimum stress part where the stress is gradually lowered on both sides of the circumferential direction from the maximum stress part,
The circumferential area including the maximum stress part between the minimum stress parts is enlarged with a constant pressing force, and at least in the final processing stage, the area in the circumferential direction including the maximum stress part is processed to have a fatigue strength commensurate with the maximum stress part, and the circumference of the maximum stress part is increased. The regions in the circumferential direction between both end sides and the minimum stress portion are respectively defined as pressure force transition regions, and in each transition region, processing is performed using a pressure force lower than the above-mentioned constant pressure force as an upper limit.

Furthermore, in the second technical means, in a roll processing method in which a flat roller and a curved roller are pressed against an axial fillet portion having different stress distributions in the circumferential direction to form a hardened layer, , find a stress distribution that has a minimum stress part where the stress is gradually lower on both sides of the circumference than the maximum stress part, and apply a constant pressure stepwise to the circumferential region containing the maximum stress part between the minimum stress parts. and processed to have a fatigue strength commensurate with the maximum stress part at least in the final processing stage, and the circumferential regions on both circumferential ends of the maximum stress part and the circumferential region between the minimum stress part are respectively pressure force transition regions. In each of these transition regions, processing is performed by increasing the pressing force stepwise between the above-mentioned constant pressing force as an upper limit and a lower pressing force.

In other words, the broken part of the pin fillet (the fourth
(see reference numeral 8 in the figure) to prevent the curved roller from falling off.
Instead of rolling the entire circumference, partial rolling is performed in the circumferential direction according to the stress distribution acting on the pin fillet. Specifically, as shown in FIG. 2, rolling is performed all at once or in stages while reciprocating between points A and D, where the stress distribution E acting on the pin fillet rises. In addition, the pressure pattern includes transition regions Ll and L2, that is, AB,
Provide a CD.

(Structure of the Invention) The processing equipment used in the method of the present invention has the same feature as the roller shown in Fig. 3 and a curved roller, and both rollers are pressed against the pin fillet portion to form a hardened layer. .

In this case, prior to rolling, a stress distribution is found in the circumferential direction of the axial fillet portion that has first and second minimum stress portions where the stress is gradually lower on both sides of the circumferential direction than the maximum stress portion.

This stress distribution E is actually measured using, for example, a strain gauge. Assume that the actual measurement result is the stress distribution E shown in FIG. 10 in the figure is the fatigue strength of the base material, but considering the stress distribution E, there is no margin at the pin bottom portion 3B, which is the maximum stress portion E1. For this reason, a hardened layer is formed by pressing the flat roller 4 and the curved roller 5 and rolling. At this time, in the conventional method, the entire circumference was rolled to increase the fatigue strength of the base material to the condition 1) to provide a margin for the pin bottom portion 3B. However, with this method, an area that does not require processing based on the stress distribution E (the shaded area 12 in the figure) is processed, which results in extra time being spent. Therefore, in order to solve only the time problem, the pressure pattern 13 in FIG. 2 can be considered. However, with this method, the pressure rises rapidly at the minimum stress portions at points A and D, resulting in a sudden change in hardness at these portions. As a result, the fatigue strength of the base material is also 1
As shown in 4 (it rapidly decreases at points A and D, this causes cranking at that part. Therefore, in the method of the present invention,
The pressure pattern 15 shown in FIG. 2 was adopted. When implementing this pressure pattern, it is necessary to determine the required processing range AD. This is determined by actually measuring the stress distribution as described above. Next, in order to avoid sudden changes in pressure at points A and D, pressure is controlled so that the pressure gradually increases or decreases in the transition areas AB and CD, and by forward and reverse rotation of the crankshaft, points A and D are Perform reciprocating processing in the required number of stages. As a result, the fatigue strength of the base material does not suddenly decrease at points A and D, and the fatigue strength increases in accordance with the stress distribution, as shown by reference numeral 16 in FIG. 2.

That is, in the present invention, the circumferential region L3 including the maximum stress portion E1 between the minimum stress portions A and B is increased all at once or in stages with a constant pressing force, and the maximum stress is increased at least in the final processing stage. Fatigue strength commensurate with part E11)
Processed to have the following.

The circumferential regions between both ends of the circumferential region L3 including the maximum stress portion E1 and the minimum stress portions A and B are pressure force transition regions Ll and L2, respectively, and in each transition region LIL2, the above-mentioned constant pressure force is applied. The process is carried out all at once to the final stage with a pressure lower than this limit, or by increasing and decreasing the pressure in stages.

(Example) In FIG. 1, the stress distribution E of the bottle fillet portion 3 of the crankshaft to be processed was determined. Therefore, in the embodiment, the transition regions Ll and L2 are set to 15°, and the required machining range LL
+L2 +L3 =L4 was set to 210°. In addition, as for the processing device, a prototype machine specifically made for an integrated crankshaft similar to that shown in FIG. 3 was used. During processing, a curved roller is first set at point A, and the pressure is gradually increased to point B while controlling the pressure using a sequencer. From point B to point 0, the pressure is kept constant and 0.
In the range from point to point D, on the contrary, the pressure is gradually decreased,
Stop the rotation of the crankshaft at point D. Next, the crankshaft is reversed and the above-described machining pattern is reversed from point D to point A. In this case, the pressure between BC is increased little by little higher than the previous pressure, and processing is performed for the required number of stages. In this example, nine stages of processing were performed. Figure 1 shows the pressure pattern and the amount of increase in fatigue strength.

Further, Table 1 below shows a comparison between this example and the rate of increase in fatigue strength at the pin bottom portion of a crankshaft that has been rolled all around. From Table 1, it can be said that the fatigue strength of both specimens showed a similar rate of increase, and that there was no problem even with partial roll processing.

Table 1 Fatigue strength increase rate In the above-described configuration and examples, an integral crankshaft is shown as the workpiece, but an assembled crankshaft or a cam with a pin may be used.

Further, regarding the journal fillet portion 7 shown in FIG. 4, it is assumed that the processed evaporator 1) is used.

Furthermore, it is optional whether or not the pressure areas of the roller 4 and the curved roller 5 are partially overlapped (see Japanese Patent Publication No. 10818/1983).

Further, in the embodiment, the roll processing range L4 is 210 degrees, and the hardness transition regions L1 and L2 are 15 degrees, but it is clear that this is not the case.

Further, in the case of a small crankshaft, it is possible to process the crankshaft all the way to the final stage without increasing the pressure in stages.

(Effect of the invention) According to the present invention, there are the following advantages.

■ Roll processing can be carried out efficiently even on pins where the fissure/throat is interrupted at the top.

■ Since there is no need to add extra thickness, the associated machining time is also eliminated.

■ Yield is also improved because there is no excess meat.

[Brief explanation of the drawing]

FIG. 1 is a graph showing a pressure pattern of an embodiment of the present invention, FIG. 2 is a graph showing a pressure pattern comparing the present invention and a conventional example, and FIG. 3 is a front view showing processing examples according to the present invention and a conventional example. 4 and 6 are front views showing a crankshaft as an example of the object to be processed according to the present invention and a conventional example, and FIG. 5 is a diagram showing a state of stress distribution. 3...Shaft fillet part (pin fillet part), 4...
- Flat roller, 5... Curved roller, 15... Pressure pattern, Ll, L2... Transition area, L3... Machining area including maximum stress, El... Maximum stress portion, E...・Stress distribution.

Claims (2)

[Claims] (1) In the axial fillet part where the stress distribution differs in the circumferential direction,
In a roll processing method in which a hardened layer is formed by pressing a flat roller and a curved roller, the stress has a minimum stress part where the stress gradually decreases on both sides of the circumference from the maximum stress part in the circumferential direction of the shaft fillet part. Find the distribution, increase the circumferential area including the maximum stress part between the minimum stress parts with a constant pressing force, and process it so that it has fatigue strength commensurate with the maximum stress part at least at the final processing stage, and then increase the maximum stress. The circumferential region between both ends of the part in the circumferential direction and the minimum stress portion is each defined as a pressure force transition region, and in each transition region, machining is performed with the above-mentioned constant pressure being the upper limit and a pressure lower than this. A method of rolling a shaft fillet portion with a characteristic different stress distribution. (2) In the axial fillet part where the stress distribution differs in the circumferential direction,
In a roll processing method in which a hardened layer is formed by pressing a flat roller and a curved roller, the stress has a minimum stress part where the stress gradually decreases on both sides of the circumference from the maximum stress part in the circumferential direction of the shaft fillet part. The distribution is found, and the circumferential region including the maximum stress portion between the minimum stress portions is processed to have a fatigue strength commensurate with the maximum stress portion at least at the final processing stage by increasing a constant pressing force step by step. , the circumferential region between both circumferential ends of the maximum stress portion and the minimum stress portion is defined as a pressure transition region, and in each transition region, the above-mentioned constant pressure is the upper limit, and steps are applied between lower pressure. A roll processing method for an axial fillet portion having different stress distributions, characterized in that processing is performed by increasing and decreasing the pressing force.